Ink-jet recording methods enable highly precise image recording by using a relatively simple apparatus and has achieved rapid progress in various fields. The use thereof ranges widely and a recording medium or inks suitable for the individual purpose are employed.
Recently, marked enhancement of recording speed has been achieved and there have been developed printers suitable for short printing runs.
However, special ink-jet paper is needed to derive the best performance of an ink-jet printer.
Recording on coated paper or art paper which exhibits little ink-absorptivity or on plastic resin film exhibiting no absorptivity produces problems such as chromatic bleeding in which different color inks are mixed on the recording medium, easily causing color contamination, which has become a problem to be solved to enable use of a variety of recording media for ink-jet recording.
Proposed to solve the foregoing problem was an ink-jet ink, which was curable upon exposure to ultraviolet rays, as disclosed in U.S. Pat. No. 4,228,438. There was also proposed a non-aqueous ink which contained an indispensable pigment and a polyacrylate having a valence of 3 or more as a polymerizable material and also contained a ketone or an alcohol as a main solvent, as disclosed in JP-B No. 5-64667 (hereinafter, the term JP-A refers to Japanese Patent Application Publication).
There was also proposed an ink using an aqueous ultraviolet-polymerizable monomer, as disclosed in JP-A No. 7-224241 (hereinafter, the term JP-A refers to Japanese Patent Application Publication) . This ink, which was curable by a curing component, was able to record even onto a non-absorptive medium but contained a large amount of a curing component other than the colorant. This component was non-volatile so that ink dots rose on the recording surface, resulting in unnatural image quality, specifically in glossiness.
To reduce this unnaturalness, reduction of the ink quantity ejected from the recording head was proposed but it resulted in a reduced dot diameter formed by a single droplet, and requiring marked enhancement of recording resolution.
As a means for enhancing recording resolution, for instance, it is theoretically feasible to increase the number of ink dots deposited on a recording medium, per unit length by increasing the number of nozzles in the recording head per unit length, however, it requires extremely precise techniques to manufacture such a recording head, producing problems such as increased manufacturing cost. Marked acceleration of the timing of ejection by a recording head is also theoretically feasible, which is technically difficult under current situations.
Even if high resolution recording is achieved, the use of conventional inks was unable to overcome unnaturalness in glossiness of both the image area and a white background.